(1) Field of the Invention
The present invention relates to benzimidazole derivatives having a cyclopropylmethyloxy group on the benzene ring, processes for preparing such compounds, and pharmaceutical compositions such a compound as an active ingredient. The benzimidazole derivatives according to the present invention exhibit excellent stability during storage and can be used for the treatment of gastric and duodenal ulcers.
(2) Description of the Prior Art
In recent years, the behavior of the potassium ion-dependent adenosine triphosphatase [hereinafter referred to as "(H.sup.+ +K.sup.+)-ATPase"], which takes part in the production of hydrochloric acid in the vesicles of gastric endoplasmic reticulum, has received attention in the pathologic physiology of gastric and duodenal ulcers, and the activity of inhibiting the enzyme has become an indicator for antiulcer agents [Gastroenterology, Vol. 1, p. 420 (1943); and ibid., Vol. 73, p 921 (1977)]. From the above viewpoint, extensive clinical investigation has been made on 5-methoxy-2-[2-(4-methoxy-3,5-dimethyl)-pyridylmethylsulfinyl]benzimidazol e (hereinafter referred to as "omeprazole") [Japanese Patent Laid-Open No. 141,783/79; and British Medical Journal, Vol. 287, p. 12 (1983)].
However, a problem arises on the stability of omeprazole, since it is degraded at an unexpectedly high rate when stored without any special precautions being taken. In order to solve this problem, it is required to convert omeprazole into its salts (Japanese Patent Laid-Open No. 167,587/84).